# CVE-2025-40263: Input: cros_ec_keyb - fix an invalid memory access

> A null pointer dereference in the Chrome OS EC keyboard driver causes a kernel crash when processing specific events without proper initialization.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 4 Dec 2025
- **Updated:** 2 Jun 2026
- **Also known as:** BELL-CVE-2025-40263, DEBIAN-CVE-2025-40263, GHSA-r3v3-c3jq-3938, ROOT-OS-DEBIAN-12-CVE-2025-40263, ROOT-OS-DEBIAN-13-CVE-2025-40263, ROOT-OS-UBUNTU-2204-CVE-2025-40263, ROOT-OS-UBUNTU-2404-CVE-2025-40263, UBUNTU-CVE-2025-40263

## What is CVE-2025-40263?

CVE-2025-40263 is a vulnerability in Linux, published on 4 Dec 2025. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

Input: cros_ec_keyb - fix an invalid memory access

If cros_ec_keyb_register_matrix() isn't called (due to
`buttons_switches_only`) in cros_ec_keyb_probe(), `ckdev->idev` remains
NULL.  An invalid memory access is observed in cros_ec_keyb_process()
when receiving an EC_MKBP_EVENT_KEY_MATRIX event in cros_ec_keyb_work()
in such case.

  Unable to handle kernel read from unreadable memory at virtual address 0000000000000028
  ...
  x3 : 0000000000000000 x2 : 0000000000000000
  x1 : 0000000000000000 x0 : 0000000000000000
  Call trace:
  input_event
  cros_ec_keyb_work
  blocking_notifier_call_chain
  ec_irq_thread

It's still unknown about why the kernel receives such malformed event,
in any cases, the kernel shouldn't access `ckdev->idev` and friends if
the driver doesn't intend to initialize them.

## Which versions are affected by CVE-2025-40263?


## How do I fix CVE-2025-40263?

Apply the vendor's patch.

## Is CVE-2025-40263 being exploited?

There is no known exploitation of CVE-2025-40263 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-40263 and fix it if it is affected.

What it is: CVE-2025-40263 is a vulnerability in Linux, published on 4 Dec 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-40263 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-40263/ (Markdown: https://insights.sbomify.com/CVE-2025-40263/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-40263
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-40263
- OSV: https://osv.dev/vulnerability/CVE-2025-40263

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-40263/
Summaries are generated and may contain mistakes; the official description above is the record.